Add cron, the core of the job system
authorSverre Rabbelier <srabbelier@gmail.com>
Sat, 18 Apr 2009 14:04:11 +0000
changeset 2211 f7497180d037
parent 2210 1095b52ed667
child 2212 4095892a3c99
Add cron, the core of the job system Patch by: Sverre Rabbelier
app/soc/cron/__init__.py
app/soc/cron/job.py
app/soc/views/models/cron.py
app/soc/views/sitemap/build.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/app/soc/cron/__init__.py	Sat Apr 18 14:04:11 2009 +0000
@@ -0,0 +1,16 @@
+#
+# Copyright 2009 the Melange authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""This module contains Melange cron jobs."""
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/app/soc/cron/job.py	Sat Apr 18 14:04:11 2009 +0000
@@ -0,0 +1,143 @@
+#!/usr/bin/python2.5
+#
+# Copyright 2009 the Melange authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Cron jobs.
+"""
+
+__authors__ = [
+    '"Sverre Rabbelier" <sverre@rabbelier.nl>',
+  ]
+
+
+import logging
+
+from google.appengine.ext import db
+from google.appengine.runtime import DeadlineExceededError
+
+from soc.models.job import Job
+
+
+class Handler(object):
+  """A handler that dispatches a cron job.
+
+  The tasks that are mapped into tasks will be called when a worker
+  has claimed the job. However, there is no guarantee as to how long
+  the task will be allowed to run. If an Exception is raised the task
+  is automatically rescheduled for execution.
+  """
+
+  def __init__(self):
+    """Constructs a new Handler with all known jobs set.
+    """
+
+    self.tasks = {}
+    self.tasks['sendAcceptanceEmail'] = logging.info
+
+  def claimJob(self, job_key):
+    """A transaction to claim a job.
+    """
+
+    job = Job.get_by_id(job_key)
+
+    if job.status != 'waiting':
+      raise db.Rollback()
+
+    job.status = 'started'
+
+    if job.put():
+      return job
+    else:
+      return None
+
+  def freeJob(self, job_key):
+    """A transaction to free a job.
+    """
+
+    job = Job.get_by_id(job_key)
+
+    job.status = 'waiting'
+
+    return job.put()
+
+  def failJob(self, job_key):
+    """A transaction to fail a job.
+    """
+
+    job = Job.get_by_id(job_key)
+
+    job.errors += 1
+
+    if job.errors > 5:
+      job.status = 'aborted'
+    else:
+      job.status = 'waiting'
+
+    job_id = job.key().id()
+    logging.warning("job %d now failed %d time(s)" % (job_id, job.errors))
+
+    return job.put()
+
+  def finishJob(self, job_key):
+    """A transaction to finish a job.
+    """
+
+    job = Job.get_by_id(job_key)
+    job.status = 'finished'
+
+    return job.put()
+
+  def abortJob(self, job_key):
+    """A transaction to abort a job.
+    """
+
+    job = Job.get_by_id(job_key)
+    job.status = 'aborted'
+
+    return job.put()
+
+  def handle(self, job_key):
+    """Handle one job.
+    """
+
+    try:
+      job = db.run_in_transaction(self.claimJob, job_key)
+
+      if not job:
+        # someone already claimed the job
+        return True
+
+      if job.task_name not in self.tasks:
+        logging.error("Unknown job %s" % job.task_name)
+        db.run_in_transaction(self.abortJob, job_key)
+        return True
+
+      task = self.tasks[job.task_name]
+
+      # excecute the actual job
+      task(job)
+
+      db.run_in_transaction(self.finishJob, job_key)
+      return True
+    except DeadlineExceededError, exception:
+      db.run_in_transaction(self.freeJob, job_key)
+      return False
+    except Exception, exception:
+      logging.exception(exception)
+      db.run_in_transaction(self.failJob, job_key)
+      return True
+
+
+handler = Handler()
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/app/soc/views/models/cron.py	Sat Apr 18 14:04:11 2009 +0000
@@ -0,0 +1,126 @@
+#!/usr/bin/python2.5
+#
+# Copyright 2009 the Melange authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Views for Cron.
+"""
+
+__authors__ = [
+    '"Sverre Rabbelier" <sverre@rabbelier.nl>',
+  ]
+
+
+from django import forms
+from django import http
+
+from soc.logic import cleaning
+from soc.logic import dicts
+from soc.logic.models.priority_group import logic as priority_group_logic
+from soc.logic.models.job import logic as job_logic
+from soc.views.helper import access
+from soc.views.helper import decorators
+from soc.views.helper import dynaform
+from soc.views.helper import widgets
+from soc.views.models import base
+
+import soc.cron.job
+
+
+class View(base.View):
+  """View methods for the Cron model.
+  """
+
+  def __init__(self, params=None):
+    """Defines the fields and methods required for the base View class
+    to provide the user with list, public, create, edit and delete views.
+
+    Params:
+      params: a dict with params for this View
+    """
+
+    rights = access.Checker(params)
+
+    new_params = {}
+    new_params['rights'] = rights
+    new_params['logic'] = priority_group_logic
+
+    new_params['name'] = "Cron"
+
+    new_params['django_patterns_defaults'] = [
+        (r'^%(url_name)s/(?P<access_type>add)$',
+          'soc.views.models.%(module_name)s.add', 'Add %(name_short)s'),
+        (r'^%(url_name)s/(?P<access_type>poke)$',
+          'soc.views.models.%(module_name)s.poke', 'Poke %(name_short)s'),
+        ]
+
+    params = dicts.merge(params, new_params)
+
+    super(View, self).__init__(params=params)
+
+  def add(self, request, access_type, page_name):
+    group = priority_group_logic.getGroup(priority_group_logic.EMAIL)
+
+    fields = {
+        'priority_group': group,
+        'task_name': 'sendAcceptanceEmail',
+        'text_data': "O HI THAR",
+        }
+
+    job_logic.updateOrCreateFromFields(fields)
+
+    return http.HttpResponse("Done")
+
+  def poke(self, request, access_type, page_name):
+    """
+    """
+
+    order = ['-priority']
+    query = priority_group_logic.getQueryForFields(order=order)
+    groups = priority_group_logic.getAll(query)
+    handler = soc.cron.job.handler
+
+    groups_completed = 0
+    jobs_completed = 0
+
+    for group in groups:
+      filter = {
+          'priority_group': group,
+          'status': 'waiting',
+          }
+
+      query = job_logic.getQueryForFields(filter=filter)
+      jobs = job_logic.getAll(query)
+
+      for job in jobs:
+        job_key = job.key().id()
+        good = handler.handle(job_key)
+
+        if not good:
+          break
+
+        jobs_completed += 1
+
+      groups_completed += 1
+
+    response = 'Completed %d jobs and %d groups completed.' % (
+        jobs_completed, groups_completed)
+
+    return http.HttpResponse(response)
+
+
+view = View()
+
+add = view.add
+poke = view.poke
--- a/app/soc/views/sitemap/build.py	Sat Apr 18 14:03:49 2009 +0000
+++ b/app/soc/views/sitemap/build.py	Sat Apr 18 14:04:11 2009 +0000
@@ -28,6 +28,7 @@
 #from soc.views.models import club_app
 #from soc.views.models import club_admin
 #from soc.views.models import club_member
+from soc.views.models import cron
 from soc.views.models import document
 from soc.views.models import host
 from soc.views.models import job
@@ -83,6 +84,7 @@
 #sitemap.addPages(club_admin.view.getDjangoURLPatterns())
 #sitemap.addPages(club_app.view.getDjangoURLPatterns())
 #sitemap.addPages(club_member.view.getDjangoURLPatterns())
+sitemap.addPages(cron.view.getDjangoURLPatterns())
 sitemap.addPages(document.view.getDjangoURLPatterns())
 sitemap.addPages(host.view.getDjangoURLPatterns())
 sitemap.addPages(job.view.getDjangoURLPatterns())